U.S. Pat. No. 6,601,634 B2 discloses a window cover apparatus that includes a window cover substrate and a mechanism for adjusting the configuration of the substrate relative to a window. Illuminating material such as phosphorescent material is provided on or in the substrate to provide illumination in darkness. The illuminating material may contain a color pigment and may be configured to provide a colorful design in both daylight and darkness.
Environmental influences like humidity affect the illuminating material adversely, thereby reducing the lifetime of the window cover apparatus.